The processing steps for silver halide color photographic light sensitive materials are basically comprised of a color developing step and a desilvering step. The desilvering step is comprised of a bleaching step and a fixing step or a bleach-fixing step. Other processing steps, such as rinsing steps and stabilizing steps may be added as additional processing steps.
Silver halides exposed to light are reduced to silver in a color developing step, and at the same time, an oxidized aromatic primary amine developing agent forms a dye upon reaction with a coupler. In the desilvering step, the reduced silver, oxidized in the color developing step, is then dissolved out in the form of silver ions into a processing solution.
As light sensitive materials are continuously processed, the bleacher becomes fatigued by the color developer brought into from, for example, the preceding tank. Where a continuous process is carried out using an ordinary automatic processor, means are taken to replenish the replenisher to keep the processing characteristics constant. When replenishing the replenisher, a large amount of overflow is inevitably produced and discarded, raising serious problems from both economical and pollutive viewpoints. For reducing the above-mentioned overflow, many proposals have been made and put into practical application, including a method in which a regenerant is added into the overflow so that the resulting solution may be used as a replenisher and a method in which a small amount of a concentrated replenisher is added to the processing solution.
Among these proposals, the method of regenerating an overflow requires a space for a stock tank or the like and photofinishers are required to carry out complicated operations. Particularly it is difficult to introduce this regeneration method into the increasing number of small-scale photofinishers such as on-site photofinishers (so-called mini-labs.) In contrast to the above-mentioned method, the method of replenishing with a small amount of a concentrated solution is satisfactory for small-sized photofinishers, such as mini-labs, because space is saved and extra apparatus is not needed. However, this method also has some defects.
Problems exist when dissolving a bleacher in a small amount of water to prepare a concentrated replenisher. No constant processing characteristics can be displayed, and filters provided in the circulation line become clogged with the deposition of the bleacher component or the replenishing pump is damaged because the solubility of the bleacher is low.
Further in the conventional replenishing systems, the disposal of plastic bottles commonly used is a serious problem. In Europe and America, legal limits are being imposed. For example, use of any plastics are forbidden, plastics must be recycled or decomposable plastics must be used.
To try to solve the above-mentioned problems, Japanese Patent Publication Open to Public Inspection (JP OPI Publication) No. 3-39739/1991 discloses a technique for granulating a bleacher. However, there is a high possibility the solubility of the granulated bleacher will deteriorate when aged in storage, or workers' health may be affected by dispersion of the fine powder of the granulated bleacher during dissolution.
JP OPI Publication No. 51-61837/1976 proposes a tablet-shaped processing composition capable of displaying the advantages of a dried composition. An inherent defect of a tablet-shaped composition is that the solubility thereof is inferior to granulated compositions. However, this patent discloses a technique whereby an expansion-cracking aqueous colloid is contained in a tablet-shaped chemical, to enhance the solubility of the tablet in water. However, when the macromolecular polymerized colloid was used, the bleaching characteristics of the tablet deteriorated under current rapid-processing conditions. It has, therefore, been difficult to use conventional techniques to provide any solid compositions having excellent solubility and rapid bleaching characteristics.
Another problem is that the above-mentioned conventional solid bleaching compositions have a low degree of moisture tolerance and, when stored for a long period, moisture must be shut out by sealing with vinyl, plastic or aluminum foil. This provides not only problems of discarding the packaging materials used which still remain unsolved, but also requires special air-conditioning systems for the manufacturing of the compositions and the packaging steps.